Immunogenetic Variation and Differential Pathogen Exposure in Free-Ranging Cheetahs across Namibian Farmlands

Aines Castro-Prieto,Simone Sommer,Heribert Hofer,Bettina Wachter,Susanne Thalwitzer,Joerg Melzheimer,Wayne M Getz

doi:10.1371/journal.pone.0049129

Aines Castro-Prieto, Simone Sommer + Show 5 more

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https://doi.org/10.1371/journal.pone.0049129

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Journal: PLoS ONE	Publication Date: Nov 7, 2012
Citations: 52	License type: CC BY 4.0

Affiliation: Leibniz Institute for Zoo and Wildlife Research

Abstract

BackgroundGenes under selection provide ecologically important information useful for conservation issues. Major histocompatibility complex (MHC) class I and II genes are essential for the immune defence against pathogens from intracellular (e.g. viruses) and extracellular (e.g. helminths) origins, respectively. Serosurvey studies in Namibian cheetahs (Acinonyx juabuts) revealed higher exposure to viral pathogens in individuals from north-central than east-central regions. Here we examined whether the observed differences in exposure to viruses influence the patterns of genetic variation and differentiation at MHC loci in 88 free-ranging Namibian cheetahs.Methodology/Principal FindingsGenetic variation at MHC I and II loci was assessed through single-stranded conformation polymorphism (SSCP) analysis and sequencing. While the overall allelic diversity did not differ, we observed a high genetic differentiation at MHC class I loci between cheetahs from north-central and east-central Namibia. No such differentiation in MHC class II and neutral markers were found.Conclusions/SignificanceOur results suggest that MHC class I variation mirrors the variation in selection pressure imposed by viruses in free-ranging cheetahs across Namibian farmland. This is of high significance for future management and conservation programs of this species.

Highlights

Genetic variation at adaptive gene loci provides direct information on selective processes involving the interaction of individuals with their environment and their capacity for future adaptive changes [1,2]
Overall genetic diversity pattern A total of six and four nucleotide sequences corresponding to Major histocompatibility complex (MHC) I exon 2 (229 bp) and MHC II-DRB exon 2 (246 bp) alleles, respectively, were observed in 88 cheetahs from Namibia
We identified in this study seven and three genotypes for the six and four expressed alleles at the MHC class I (MHC I) and II-DRB loci, respectively (Table 1)

Summary

Introduction

Genetic variation at adaptive gene loci provides direct information on selective processes involving the interaction of individuals with their environment and their capacity for future adaptive changes [1,2]. Heterozygous individuals (heterozygote advantage, overdominance [10]), or individuals carrying highly dissimilar alleles (divergentallele advantage [10,11]) are capable of initiating an appropriate immune response against a more diverse array of pathogens than homozygous individuals or individual with more similar alleles These non-exclusive hypotheses have been studied by testing associations of specific MHC alleles with pathogens, the proportions of genotypes within populations, patterns of population structure, and the effects of genetic distance between genotypes [2,12]. The majority of these studies focused on MHC II genotyping and simultaneously scanned for different types of pathogens of extracellular origin in the same individuals [12,13]. We examined whether the observed differences in exposure to viruses influence the patterns of genetic variation and differentiation at MHC loci in 88 free-ranging Namibian cheetahs

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